U.S. patent application number 13/668360 was filed with the patent office on 2014-05-08 for method and apparatus for wireless power transmission.
This patent application is currently assigned to O2MICRO INC.. The applicant listed for this patent is O2MICRO INC.. Invention is credited to Jun Chen, Fan Dou, James Wang, Jun Wang, Qiang Wang.
Application Number | 20140125139 13/668360 |
Document ID | / |
Family ID | 49328440 |
Filed Date | 2014-05-08 |
United States Patent
Application |
20140125139 |
Kind Code |
A1 |
Wang; Jun ; et al. |
May 8, 2014 |
METHOD AND APPARATUS FOR WIRELESS POWER TRANSMISSION
Abstract
Method and apparatus for wireless power transmission. A first
target level of a parameter associated with the electric power is
sent to the transmitting device. The electric power is then
received from the transmitting device. When the parameter of the
received electric power reaches the first target level, a second
target level of the parameter is sent to the transmitting device.
The second target level of the parameter is determined based on a
magnitude of a load coupled to the receiving device.
Inventors: |
Wang; Jun; (Chengdu, CN)
; Wang; Qiang; (Chengdu, CN) ; Dou; Fan;
(Chengdu, CN) ; Chen; Jun; (Chengdu, CN) ;
Wang; James; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
O2MICRO INC. |
Santa Clara |
CA |
US |
|
|
Assignee: |
O2MICRO INC.
Santa Clara
CA
|
Family ID: |
49328440 |
Appl. No.: |
13/668360 |
Filed: |
November 5, 2012 |
Current U.S.
Class: |
307/104 |
Current CPC
Class: |
H02J 50/10 20160201;
H02J 7/00034 20200101; H02J 50/80 20160201; H02J 50/12 20160201;
H02J 7/025 20130101; H02J 50/60 20160201 |
Class at
Publication: |
307/104 |
International
Class: |
H02J 17/00 20060101
H02J017/00 |
Claims
1. A method for a receiving device to wirelessly receive electric
power from a transmitting device, the method comprising the steps
of: sending a first target level of a parameter associated with the
electric power to the transmitting device; receiving the electric
power from the transmitting device; and when the parameter of the
received electric power reaches the first target level, sending a
second target level of the parameter to the transmitting device,
wherein the second target level of the parameter is determined
based on a magnitude of a load coupled to the receiving device.
2. The method of claim 1, wherein the parameter is at least one of
voltage, current, and power.
3. The method of claim 1, wherein the first target level of the
parameter is higher than the second target level of the
parameter.
4. The method of claim 1, wherein the first target level of the
parameter is determined regardless of the magnitude of the
load.
5. The method of claim 1, further comprising the steps of: once the
parameter of the received electric power reaches the first target
level, coupling the load to the receiving device; detecting the
magnitude of the load; and determining the second target level of
the parameter based on the magnitude of the load.
6. The method of claim 1, further comprising the steps of: upon
receiving, the first target level of the parameter, adjusting, by
the transmitting device, a frequency of the electric power based on
the first target level of the parameter; and upon receiving the
second target level of the parameter, adjusting, by the
transmitting device, the frequency of the electric power based on
the second target level of the parameter.
7. The method of claim 1, further comprising the step of: when the
parameter associated with the received electric power has not
reached the first target level for a first time period, coupling
the load to the receiving device after a second time period.
8. The method of claim 7, further comprising the step of:
adjusting, by the transmitting device, a frequency of the electric
power based on a maximum power capacity of the transmitting
device.
9. The method of claim 1, wherein the magnitude of the load
corresponds to a level of load current.
10. An apparatus comprising a receiving device comprising: a power
reception unit configured to wirelessly receive electric power from
a transmitting device; a control unit operatively coupled to the
power reception unit and configured to: control sending of a first
target level of a parameter associated with the electric power to
the transmitting device, and when the parameter of the received
electric power reaches the first target level, control sending of a
second target level of the parameter to the transmitting device,
wherein the second target level of the parameter is determined
based on a magnitude of a load coupled to the receiving device; and
a communication unit operatively coupled to the power reception
unit and the control unit and configured to send the first and
second target levels of the parameter to the transmitting
device.
11. The apparatus of claim 10, wherein the parameter is at least
one of voltage, current, and power.
12. The apparatus of claim 10, wherein the first target level of
the parameter is higher than the second target level of the
parameter.
13. The apparatus of claim 10, further comprising a load and a
switch configured to control coupling of the load to the receiving
device.
14. The apparatus of claim 13, wherein the switch is configured to
decouple the load from the receiving device before the first target
level of the parameter is determined.
15. The apparatus of claim 13, wherein the switch is configured to,
once the parameter of the received electric power reaches the first
target level, couple the load to the receiving device; and the
control unit is further configured to: detect the magnitude of the
load, and determine the second target level of the parameter based
on the magnitude of the load.
16. The apparatus of claim 13, wherein the switch is configured to,
when the parameter associated with the received electric power has
not reached the first target level for a first time period, couple
the load to the receiving device after a second time period.
17. The apparatus of claim 10, wherein the magnitude of the load
corresponds to a level of load current.
18. A system for wireless power transmission comprising: a
receiving device comprising: a power reception unit configured to
wirelessly receive electric power from a transmitting device; a
control unit operatively coupled to the power reception unit and
configured to: control sending of a first target level of a
parameter associated with the electric power to the transmitting
device, and when the parameter of the received electric power
reaches the first target level, control sending of a second target
level of the parameter to the transmitting device, wherein the
second target level of the parameter is determined based on a
magnitude of a load coupled to the receiving device; and a
communication unit operatively coupled to the power reception unit
and the control unit and configured to send the first and second
target levels of the parameter to the transmitting device; and a
transmitting device comprising a power transmission unit configured
to wirelessly transmit the electric power to the receiving device
at a frequency determined based on the first and second target
levels of the parameter.
19. The system of claim 18, further comprising a load and a switch
configured to control coupling of the load to the receiving
device.
20. The system of claim 19, wherein the switch is configured to
decouple the load from the receiving device before the first target
level of the parameter is determined.
21. The system of claim 19, wherein the switch is configured to,
once the parameter of the received electric power reaches the first
target level, couple the load to the receiving device; and the
control unit of the receiving device is further configured to:
detect the magnitude of the load, and determine the second target
level of the parameter based on the magnitude of the load.
22. The system of claim 18, wherein the transmitting device further
comprises a control unit configured to: upon receiving the first
target level of the parameter, adjust the frequency of the
transmitted electric power based on the first, target level of the
parameter; and upon receiving the second target level of the
parameter, adjust the frequency of the transmitted electric power
based on the second target level of the parameter.
23. The system of claim 19, wherein the switch is configured to,
when the parameter associated with the received electric power has
not reached the first target level for a first time period, couple
the load to the receiving device after a second time period.
24. The system of claim 23, wherein the transmitting device further
comprises a control unit configured to, when the parameter
associated with the received electric power has not reached the
first target level for the first time period, adjust the frequency
of the transmitted electric power based on a maximum power capacity
of the transmitting device.
25. A machine-readable tangible and non-transitory medium having
information recorded thereon for wireless power transmission,
wherein the information, when read by the machine, causes the
machine to perform the following: sending, by a receiving device, a
first target level of a parameter associated with electric power to
a transmitting device; wirelessly receiving, by the receiving
device, the electric power from the transmitting device; and when
the parameter of the received electric power reaches the first
target level, sending, by the receiving device, a second target
level of the parameter to the transmitting device, wherein the
second target level of the parameter is determined based on a
magnitude of a load coupled to the receiving device.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The disclosure relates generally to a method and apparatus
for wireless power transmission.
[0003] 2. Discussion of Technical Background
[0004] Wireless power transmission is the transmission of
electrical energy from a power source to an electrical load without
interconnecting manmade conductors. The most common form of
wireless power transmission is carried out using direct induction
followed by resonant magnetic induction. Other methods include
electromagnetic radiation in the form of microwaves or lasers and
electrical conduction. Wireless power transmission has been used
for battery charging, or other suitable loads, in a wide range of
mobile devices, such as mobile phone, camera, music player,
headset, etc.
[0005] In a wireless power transmission system, the receiving
device (receiver) may provide control information to the
transmitting device (transmitter) by, for example, load modulation
on the power signal. Based on the received control information, the
transmitting device may adjust a certain parameter associated with
the transmitted electric power, e.g., the frequency, to the desired
level in order to drive the load coupled to the receiving device.
Known standards, such as QI communication protocol (Wireless Power
Consortium), define how the receiving device communicates its power
needs back to the transmitting device over the same magnetic
coupling used for power transmission. For example, after the
initial communication between the receiving and transmitting
devices is established at a default pulse-width-modulation (PWM)
frequency of 175 kHz, load is immediately coupled to the receiving
device. However, as the default PWM frequency is relatively high,
the corresponding load driving capacity of the received electric
power is relatively low. As the load, is immediately coupled to the
receiving device, the rectified voltage may suddenly drop, which is
undesirable for the receiving device. Moreover, as the current QI
communication protocol supports up to 5 W of output power, if the
load is 10 W or higher, the sudden voltage-drop may cause the
receiving device fail to drive the load.
[0006] Accordingly, there exists a need for an improved solution
for wireless power transmission to solve the above-mentioned
problems.
SUMMARY
[0007] The present disclosure describes methods, apparatus, and
programming for wireless power transmission.
[0008] In one example, a method for a receiving device to
wirelessly receive electric power from a transmitting device is
provided. A first target level of a parameter associated with the
electric power is sent to the transmitting device. The electric
power is then received from the transmitting device. When the
parameter of the received electric power reaches the first target
level, a second target level of the parameter is sent to the
transmitting device. The second target level of the parameter is
determined based on a magnitude of a load coupled to the receiving
device.
[0009] In another example, an apparatus including a receiving
device is provided. The receiving device includes a power reception
unit, a control unit, and a communication unit. The power reception
unit is configured to wirelessly receive electric power from a
transmitting device. The control unit is operatively coupled to the
power reception unit and is configured to control sending of a
first target level of a parameter associated with the electric
power to the transmitting device. The control unit is further
configured to, when the parameter of the received electric power
reaches the first target level, control sending of a second target
level of the parameter to the transmitting device. The second
target level of the parameter is determined based on a magnitude of
a load coupled to the receiving device. The communication unit is
operatively coupled to the power reception unit and the control
unit and is configured to send the first and second target levels
of the parameter to the transmitting device.
[0010] In still another example, a system for wireless power
transmission is provided. The system includes a receiving device
and a transmitting device. The receiving device includes a power
reception unit, a control unit, and a communication unit. The power
reception unit is configured to wirelessly receive electric power
from a transmitting device. The control unit is operatively coupled
to the power reception unit and is configured to control sending of
a first target level of a parameter associated with the electric
power to the transmitting device. The control unit is further
configured to, when the parameter of the received electric power
reaches the first target level, control sending of a second target
level of the parameter to the transmitting device. The second
target level of the parameter is determined based on a magnitude of
a load coupled to the receiving device. The communication unit is
operatively coupled to the power reception unit and the control
unit and is configured to send the first and second target levels
of the parameter to the transmitting device. The transmitting
device includes a power transmission unit configured to wirelessly
transmit the electric power to the receiving device at a frequency
determined based on the first and second target levels of the
parameter.
[0011] In yet another example, a machine readable and
non-transitory medium having information recorded thereon for
wireless power transmission, wherein the information, when read by
the machine, causes the machine to perform a series of steps. A
first target level of a parameter associated with electric power is
sent by a receiving, device to a transmitting device. The electric
power is then wirelessly received by the receiving device from the
transmitting device. When the parameter of the received electric
power reaches the first target level, a second target level of the
parameter is sent by the receiving device to the transmitting
device. The second target level of the parameter is determined
based on a magnitude of a load coupled to the receiving device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The embodiments will be more readily understood in view of
the following description when accompanied by the below figures and
wherein like reference numerals represent like elements,
wherein:
[0013] FIG. 1 is a block diagram illustrating an example of a
system for wireless power transmission including a transmitting
device and a receiving device, in accordance with one embodiment of
the present disclosure;
[0014] FIG. 2 is a block diagram illustrating an example of the
receiving device and load shown in FIG. 1, in accordance with one
embodiment of the present disclosure;
[0015] FIG. 3 is a block diagram illustrating an example of the
transmitting device shown in FIG. 1, in accordance with one
embodiment of the present disclosure;
[0016] FIG. 4 is a time line chart illustrating an example of
wireless power transmission, in accordance with one embodiment of
the present disclosure;
[0017] FIG. 5 is a time line chart illustrating another example of
wireless power transmission, in accordance with one embodiment of
the present disclosure;
[0018] FIG. 6 is a flow chart illustrating an example of a method
for wireless power transmission, in accordance with one embodiment
of the present disclosure;
[0019] FIG. 7 is a flow chart illustrating another example of a
method for wireless power transmission, in accordance with one
embodiment of the present disclosure;
[0020] FIG. 8 is a flow chart illustrating still another example of
a method for wireless power transmission, in accordance with one
embodiment of the present disclosure; and
[0021] FIG. 9 is a block diagram illustrating an example of a
control unit in the receiving device shown in FIG. 2 including a
processor and a memory, in accordance with one embodiment of the
present disclosure.
DETAILED DESCRIPTION
[0022] Reference will now be made in detail to the embodiments of
the present disclosure, examples of which are illustrated in the
accompanying drawings. While the present disclosure will be
described in conjunction with the embodiments, it will be
understood that they are not intended to limit the present
disclosure to these embodiments. On the contrary, the present
disclosure is intended to cover alternatives, modifications, and
equivalents, which may be included within the spirit and scope of
the present disclosure as defined by the appended claims.
[0023] Furthermore, in the following detailed description of
embodiments of the present disclosure, numerous specific details
are set forth in order to provide a thorough understanding of the
present disclosure. However, it will be recognized by one of
ordinary skill in the art that the present disclosure may be
practiced without these specific details. In other instances,
well-known methods, procedures, components, and circuits have not
been described in detail as not to unnecessarily obscure aspects of
the embodiments of the present disclosure.
[0024] Embodiments in accordance with the present disclosure
provide a method and apparatus for driving a large load by wireless
power transmission. The method and apparatus disclosed herein can
adaptively support loads with different power needs in a more
efficient manner compared with known solutions. Moreover, the
method and apparatus disclosed herein also support existing
wireless power transmission standards, such as the QI communication
protocol, and thus, are compatible with any QI-compatible
transmitting device with 5 W power capacity.
[0025] Additional advantages and novel features will be set forth
in part in the description which follows, and in part will become
apparent to those skilled in the art upon examination of the
following and the accompanying drawings or may be learned by
production or operation of the examples.
[0026] FIG. 1 illustrates one example of a system 100 for wireless
power transmission, in accordance with one embodiment of the
present disclosure. The system 100 may be any suitable wireless
power transmission system that includes a receiving device 102 and
a transmitting device 104. Electric power is wirelessly transmitted
from the transmitting device 104 to the receiving device 102 by any
known mechanism, such as but not limited to, resonant magnetic
induction, electromagnetic radiation, or electrical conduction. The
same mechanism for power transmission may be also used for sending
control information from the receiving device 102 to the
transmitting device 104 for adjusting any electrical parameter,
such as frequency, associated with the electric power to a desired
level. The control information may include, for example, target
levels of an electrical parameter (desired operation point)
associated with the electric power, such as the desired level of
voltage, current, or power of the received electric energy.
[0027] In this example, the receiving device 102 may be part of an
apparatus 106 having a load 108 that can be coupled to be receiving
device 102. The apparatus 106 may be any suitable electronic
device, such as but is not limited to, a laptop computer, netbook
computer, digital camera, digital camcorder, handheld device (e.g.,
dumb or smart phone, tablet, etc.), gaming, console, set-top box,
music player, global positioning system (GPS), or any other
suitable device. The load 108 may be, for example, a battery
charger and one or more batteries. In other examples, the receiving
device 102 may be a discrete electronic device for providing power
to the load 108. In any event, a switch 110 may be provided between
the receiving device 102 and the load 108 to control coupling of
the load 108 to the receiving device 102. It is understood that any
other suitable component may be included in the apparatus 106.
[0028] In this example, the receiving device 102 includes a power
reception unit 112, a control unit 114, and a communication unit
116. The power reception unit 112 is configured to wirelessly
receive electric power from the transmitting device 104. The
control unit 114 in this example performs various control
functions, such as monitoring and analyzing the electrical
parameters associated with the received electric power against
desired operation points e.g., output current, voltage) and
controlling the power provided to the output load 108. The control
unit 114 is also configured to control sending of target levels of
electrical parameters associated with the electric power to the
transmitting device 104 by the communication unit 116. That is, the
control unit 114 is responsible for sending its power needs back to
the transmitting device 104. The communication unit 116 is
configured to send control information to the transmitting device
104 in accordance with a communication protocol, such as the QI
communication protocol, for example, by the same electromagnetic
coupling mechanism used for power transmission. The control
information in this example includes target levels of the
electrical parameters associated with the electric power.
[0029] The transmitting device 104 may be any suitable base station
for wirelessly providing electric, power to the receiving device
102. In this example, the transmitting device 104 includes a power
transmission unit 118, a control unit 120, and a communication unit
122. The power transmission unit 118 is configured to wirelessly
transmit the electric power to the receiving device 102 at a
certain PWM frequency. The frequency is determined by the control
unit 120 based on the received target levels of the electrical
parameters sent from the receiving device 102. The communication
unit 122 is configured to receive the control information including
the target levels of the electrical parameters from the receiving
device 102.
[0030] In this example, after the initial communication between the
transmitting and receiving devices 104, 102 is established, the
control unit 114 of the receiving device 102 first controls the
switch 110 to decouple the load 108 from the receiving device 102.
The control unit 114 of the receiving device 102 then sends a first
target level of a parameter associated with the electric power to
the transmitting device 104. The first target level of the
parameter, such as the desired output voltage, is determined
regardless of the magnitude of the load 108 as it is decoupled from
the receiving device 102. Upon receiving the first target level,
the control unit 120 of the transmitting device 104 controls the
power transmission unit 118 to adjust the PWM frequency of the
transmitted electric power accordingly. The control unit 114 of the
receiving device 102 then continually monitors the detected level
of the parameter to see if it reaches the first target level. Once
the first target level is reached, the control unit 114 is further
configured to control the switch 110 to couple the load 108 to the
receiving device 102 and determine a second target level of the
parameter based on the magnitude of the load 108 (e.g., load
current). The second target level is sent to the transmitting
device 104 and used for adaptively adjusting the PWM frequency
based on the magnitude of the load 108.
[0031] FIG. 2 illustrates one example of the receiving device 102
and load 108, in accordance with one embodiment of the present
disclosure. In this example, the load 108 includes a battery
charger 202 for charging a battery 204 using the power provided by
the receiving device 102. The receiving device 102 includes the
power reception unit 112 having a coil 206 and rectifier 208. In
this example, the coil 206 is responsible for receiving magnetic
field by its resonant circuit and converting it to an AC voltage
signal. The rectifier 208 is configured to convert the AC voltage
signal to a DC voltage signal. A DC/DC converter 210 may be
included to further convert the DC voltage signal to a desired
level for driving the load 108. An ADC monitor 212 may be employed
to detect any suitable electrical parameter associated with the
received electric power, e.g., voltage, current, or power, and
provide it to the control unit 114. The receiving device 102 in
this example also includes the communication unit 116 having a load
modulator 214 and the coil 206. The load modulator 214 is
responsible for modulating the control information, e.g., target
levels of the electrical parameters, and sending it to the
transmitting device 104 through the resonant circuit of the coil
206.
[0032] In this example, the target level of the electric parameter
may be a predetermined value regardless of the magnitude of the
load or a value adaptively determined based on the magnitude of the
load once it is coupled to the receiving device 102 through the
switch 110. In one example, as shown in FIG. 9, the control unit
114 may be implemented by one or more processors 902 and memory
904. In this example, software programs and data may be loaded into
the memory 904 and executed by the processor 902. The processor 902
may be any suitable processing unit, such as but not limited to, a
microprocessor, a microcontroller, a central processing unit, an
electronic control unit, etc. The memory 904 may be, for example, a
discrete memory or a unified memory integrated with the processor
902. The software programs may include a target level calculating
module 906 for adaptively determining the desired target level of
an electrical parameter based on the actual magnitude of the
coupled load 108. The data includes, for example, a predetermined
target level of the electrical parameter regardless of the
magnitude of the load 108. In one example, the electrical parameter
is the output voltage, and the predetermined target level of the
output voltage is set to be higher than the desired target level
determined based on the actual load magnitude.
[0033] FIG. 3 illustrates one example of the transmitting device
104, in accordance with one embodiment of the present disclosure.
In this example, the transmitting device 104 includes the power
transmission unit 118 having a PWM frequency unit 302 and a coil
304 and the communication unit 122 having a load demodulator 306
and the coil 304. The load demodulator 306 is responsible for
de-modulating the control information, e.g., target levels of the
electrical parameters, picked up by the coil 304. Based on the
target levels of the electrical parameter, the control unit 120 is
configured to determine a corresponding PWM frequency and control
the PWM frequency unit 302 to adjust the frequency to the desired
level. The PWM frequency unit 302 is responsible for converting a
DC voltage signal to an AC voltage signal, and the coil 304 is
responsible for converting the electric field of the AC voltage
signal to the magnetic field. An ADC monitor 308 may be included,
to provide levels of electrical parameters, such as voltage and
current, to the control unit 120 for foreign object detection and
over-current and over-voltage protections.
[0034] FIG. 4 is a time line chart illustrating an example of
wireless power transmission, in accordance with one embodiment of
the present disclosure. Initially, communication between the
transmitting device 104 and receiving device 102 is established at
a default frequency. According to the QI communication protocol,
the default frequency is 175 kHz. Once the initial communication is
established, the load 108 is decoupled from the receiving device
102. Without the knowledge of the magnitude of the load 108, the
receiving device 102 sets up a parameter associated with the
electric power, e.g., the output voltage, to a first target level.
It is known that the output voltage of the received electric power
corresponds to the PWM frequency and that the higher the PWM
frequency is, the lower the output voltage is. In this example, the
first target level is determined at a relative high level such that
the corresponding PWM frequency is lower than the default frequency
of 175 kHz. In one example, the first target level of the output
voltage is determined such that the corresponding frequency is 160
kHz. The lower PWM frequency corresponds to a higher load driving
capacity as known in the art. The predetermined first target level
of the parameter, e.g., output voltage, is then sent to the
transmitting device 104.
[0035] The transmitting device 104 then adjusts the PWM frequency
of the transmitted electric power to a level that is determined
based on the first target level of the parameter. In the example
mentioned above, the transmitting device 104 may try to adjust its
PWM frequency to 160 kHz such that the output voltage of the
receiving device 102 may reach the first target level. The electric
power is then transmitted to the receiving device 102 at the
frequency determined based on the first target level.
[0036] In this example, once the parameter reaches the first target
level at the receiving device 102, the load 108 is then coupled to
the receiving device 102. Based on the actual magnitude of the load
108, the receiving device 102 determines a second target level of
the parameter, e.g., output voltage, which is sufficient to drive
the load 108. The second target level of the parameter is sent to
the transmitting device 104 so that the transmitting device 104 may
adjust the PWM frequency accordingly. The electric power is then
transmitted to the receiving device 102 at the frequency determined
based on the second target level.
[0037] It is understood that the first target level of output
voltage may be set up to be higher than the second target level.
Accordingly, the receiving device 102 has a higher load driving
capacity without coupling the load in order to avoid any sudden
voltage-drop and then reduces its output voltage according to the
actual magnitude of the load 108 once the load 108 is coupled in
order to increase its efficiency. By doing so, the receiving device
102 is able to adaptively drive loads with a wide range of
magnitudes while still being compatible with existing standards,
such as the QI communication protocol. The sudden voltage-drop
happened in known solutions is also suppressed as the load 108 is
not coupled to the receiving device 102 until the output voltage
reaches a desired level.
[0038] FIG. 5 is a time line chart illustrating another example of
wireless power transmission, in accordance with one embodiment of
the present disclosure. In this example, the transmitting device
104 may be a device with relatively low load-driving capacity,
e.g., a. QI-compatible 5 W transmitting device. In this case, the
transmitting device 104 may not be able to adjust its PWM frequency
to the desired level determined based on the first target level of
the electrical parameter. As a result, the electrical parameter,
e.g., the output voltage, cannot reach the first target level at
the receiving device 102. A first time period may be predetermined
as a threshold to determine whether the transmitting device 104 has
sufficient load-driving capacity. For example, if the output
voltage cannot reach the first target level within the first time
period, the receiving device 102 may delay for a second
predetermined time period to have the transmitting device 104 reach
its maximum power capacity before coupling the load 108 to the
receiving device 102. The transmitting device 104 then transmits
the electric power at the frequency determined based on its maximum
power capacity, and the receiving device 102 now drives the load
108 with the maximum power capacity of the transmitting device 104.
In one example, for a QI-compatible 5 W transmitting device, the
receiving device 102 drives a load with 5 W power. By doing so, the
receiving device 102 is still compatible with transmitting devices
with relatively low power capacity even when they cannot reach the
desired power capacity. The sudden voltage-drop happened in known
solutions is also suppressed as the load 108 is not coupled to the
receiving device 102 until the output voltage reaches its maximum
possible level.
[0039] FIG. 6 depicts one example of a method for wireless power
transmission, in accordance with one embodiment of the present
disclosure. It will be described with reference to the above
figures. However, any suitable unit may be employed. Beginning at
block 602, a first target level of a parameter, e.g., output
voltage, associated with the electric power is sent to the
transmitting device. Proceeding to block 604, the electric power is
received from the transmitting device. For example, the PWM
frequency of the electric power may be determined based on the
first target level of the output voltage. Moving to block 606, when
the parameter of the received electric power reaches the first
target level, a second target level of the parameter is sent to the
transmitting device. The second target level of the parameter is
determined based on a magnitude of a load, e.g., load current,
coupled to the receiving device. As described above, blocks 602,
604, 606 may be performed by the receiving device 102.
[0040] FIG. 7 depicts another example of the method for wireless
power transmission, in accordance with one embodiment of the
present disclosure. It will be described with reference to the
above figures. However, any suitable unit may be employed.
Beginning at block 702, load is decoupled from the receiving
device. As described above, this may be performed by the control
unit 114 of the receiving device 102 in conjunction with the switch
110. Moving to block 704, a first target level of an electrical
parameter associated with electric power is sent to the
transmitting device. The parameter includes, for example, voltage,
current, and power. The first target level may be a predetermined
level and is determined regardless of the magnitude of the load. As
described above, this may be performed by control unit 114 in
conjunction with the communication unit 116 of the receiving device
102. At block 706, electric power with a frequency determined based
on the first target level of the parameter is received. The
frequency may be adjusted by the transmitting device according to
the first target level of the parameter. As described above, this
may be performed by the power reception unit 112 of the receiving,
device 102. Moving to block 708, level of the electrical parameter
of the received electric power is detected. For example, the output
voltage and/or current of the rectified signal is measured. As
described above, this may be performed by the ADC monitor 212 of
the receiving device 102.
[0041] At block 710, whether the electrical parameter reaches the
first target level within a predetermined time period is
determined. As described above, this may be performed by control
unit 114 of the receiving device 102. If the electrical parameter
reaches the first target level within the first time period,
process continues to block 712, where the load is coupled to the
receiving device. As described above, this may be performed by the
control unit 114 of the receiving device 102 in conjunction with
the switch 110. At block 714, the magnitude of the load, e.g., load
current, is detected. Moving to block 716, the second target level
of the electrical parameter is determined based on the detected
load magnitude. For example, the electrical parameter may be output
voltage, and the first target level of the output voltage is higher
than the second target level of the output voltage. As described
above, blocks 714, 716 may be performed by the control unit 114 of
the receiving device 102. At block 718, the second target level of
the electrical parameter is sent to the transmitting device. As
described above, this may be performed by control unit 114 in
conjunction with the communication unit 116 of the receiving device
102. At block 720, electric power with a frequency determined based
on the second target level of the parameter is received. The
frequency may be adjusted by the transmitting device according to
the second target level of the parameter. As described above, this
may be performed by the power reception unit 112 of the receiving
device 102.
[0042] FIG. 8 depicts still another example of the method for
wireless power transmission, in accordance with one embodiment of
the present disclosure. It will be described with reference to the
above figures. However, any suitable unit may be employed. At block
502, if the electrical parameter cannot reach the first target
level within the first time period at block 710, a second
predetermined time period is delayed by the receiving device.
Moving to block 804, load is coupled to the receiving device after
the delay. As described above, this may be performed by the control
unit 114 of the receiving device 102 in conjunction with the switch
110. At block 806, electric power with a frequency determined based
on the maximum power capacity of the transmitting device is
received. As described above, this may be performed by the power
reception unit 112 of the receiving device 102.
[0043] Aspects of the method for wireless power transmission, as
outlined above, may be embodied in programming. Program aspects of
the technology may be thought of as "products" or "articles of
manufacture" typically in the form of executable code and/or
associated data that is carried on or embodied in a type of machine
readable medium. Tangible non-transitory "storage" type media
include any or all of the memory or other storage for the
computers, processors or the like, or associated modules thereof,
such as various semiconductor memories, tape drives, disk drives
and the like, which may provide storage at any time for the
computer-implemented method.
[0044] All or portions of the computer-implemented method may at
times be communicated through a network such as the Internet or
various other telecommunication networks. Such communications, for
example, may enable loading of the software from one computer or
processor into another. Thus, another type of media that may hear
the elements of the computer-implemented method includes optical,
electrical, and electromagnetic waves, such as used across physical
interfaces between local devices, through wired and optical
landline networks and over various air-links. The physical elements
that carry such waves, such as wired or wireless links, optical
links or the like, also may be considered as media bearing the
computer-implemented method. As used herein, unless restricted to
tangible "storage" media, terms such as computer or machine
"readable medium" refer to any medium that participates in
providing instructions to a processor for execution.
[0045] Hence, a machine readable medium may take many forms,
including but not limited to, a tangible storage medium, a carrier
wave medium or physical transmission medium. Non-volatile storage
media include, for example, optical or magnetic disks, such as any
of the storage devices in any computer(s) or the like, which may be
used to implement the system or any of its components as shown in
the drawings. Volatile storage media include dynamic memory, such
as a main memory of such a computer platform. Tangible transmission
media include coaxial cables; copper wire and fiber optics,
including the wires that form a bus within a computer system.
Carrier-wave transmission media can take the form of electric or
electromagnetic signals, or acoustic or light waves such as those
generated during radio frequency (RF) and infrared (IR) data
communications. Common forms of computer-readable media therefore
include for example: a floppy disk, a flexible disk, hard disk,
magnetic tape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM,
any other optical medium, punch cards paper tape, any other
physical storage medium with patterns of holes, a RAM, a PROM and
EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier
wave transporting data or instructions, cables or links
transporting such a carrier wave, or any other medium from which a
computer can read programming code and/or data. Many of these forms
of computer readable media may be involved in carrying one or more
sequences of one or more instructions to a processor for
execution.
[0046] Those skilled in the art will recognize that the present
disclosure is amenable to a variety of modifications and/or
enhancements. For example, although the implementation of various
components described above may be embodied in a hardware device, it
can also be implemented as a firmware, firmware/software
combination, firmware/hardware combination, or a
hardware/firmware/software combination.
[0047] While the foregoing description and drawings represent
embodiments of the present disclosure, it will be understood that
various additions, modifications, and substitutions may be made
therein without departing from the spirit and scope of the
principles of the present disclosure as defined in the accompanying
claims. One skilled in the art will appreciate that the present
disclosure ma be used with many modifications of form, structure,
arrangement, proportions, materials, elements, and components and
otherwise, used in the practice of the disclosure, which are
particularly adapted to specific environments and operative
requirements without departing from the principles of the present
disclosure. The presently disclosed embodiments are therefore to be
considered in all respects as illustrative and not restrictive, the
scope of the present disclosure being indicated by the appended
claims and their legal equivalents, and not limited to the
foregoing description.
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